4.2. How can I make a floppy-disk-based UNIX for fsck'ing the hard drive?

Make a copy of the "Floppy Filesystem Disk" (Disk 3 of ##) of
the Foundation Set as follows. Insert the original floppy filesystem
diskette, and have a formatted, 10 sectors/track diskette ready. Type
the "fpcp" command and copy it.
Now that you have a copy, place a copy of /etc/fsck on it.
While you're at it, save your /etc/inittab in case it gets destroyed
in the future and you can't get the machine to boot.
# mount /dev/fp021 /mnt
# cp /etc/fsck /mnt/etc/fsck
# cp /etc/inittab /mnt/etc/inittab.save
# sync
# umount /dev/fp021
Now you have a disk that will help you do a standalone
filesystem check.
To use this, first boot the system using the "Floppy Boot
Disk" (Disk 2 of ##). It will stop and ask you to insert the Floppy
Filesystem Disk. Insert your copy instead. When it comes to the
first question, interrupt the script with <DEL> to get a "#" prompt.
The disk is already mounted as /mnt, so unmount it:
# umount /dev/fp002
warning: /dev/fp002 not in mount table
Do your filesystem check:
# /etc/fsck -D -S /dev/rfp002
Reboot the system:
# sync
# sync
# reboot
NOTE: the root filesystem is the floppy filesystem, so the
"-s" option to fsck salvages the floppy root filesystem, not the root
filesystem on the hard drive. This is why "-s" is not used above.
*** THE FOLLOWING IS NOT FOR THE UNINHIBITED OR CASUAL USER ***
For the real UNIX hacker out there (who is fortunate enough to
have a tape drive on your machine) you could grab the fp_unix.sh.Z,
conf.sh.Z and kern.cpio.Z files from the OSU Archives. This is a set
of tools, along with the kernel object files for 3.51m, that will let
you link in the tape driver (tp.o) to your floppy UNIX kernel and give
you full control of the tape device from the floppy UNIX. This is
very handy for doing full backups or restores from the floppy!